UE reporting in cell applying cca

Abstract

Systems and methods for measurement reporting in a cellular communications system are disclosed. In one embodiment, a method performed by a User Equipment (UE) comprises generating a measurement report for a target cell, the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell for the target cell. The method further comprises transmitting the measurement report to a Radio Access Network (RAN) node that operates the target cell. In this manner, power saving and reduced time delay in measurement reporting can be provided, e.g., in a cell subject to Clear Channel Assessment (CCA).

Description

[0001] UE REPORTING IN CELL APPL YING CCA

[0002] Technical Field

[0003] The present disclosure relates to measurement reporting in a cellular communications system.

[0004] Background

[0005] NR based Access to Unlicensed Spectrum

[0006] Next generation systems are expected to support a wide range of use cases with varying requirements ranging from fully mobile devices to stationary Internet of Things (loT) or fixed wireless broadband devices. The traffic pattern associated with many use cases is expected to consist of short or long bursts of data traffic with varying lengths of waiting periods in between, which are referred to herein as inactive states. In 3rdGeneration Partnership Project (3GPP) New Radio (NR), both License Assisted Access (LAA) and standalone unlicensed operation are to be supported. Hence, the procedure of Physical Random Access Channel (PRACH) transmission and / or Scheduling Request (SR) transmission in unlicensed spectrum is investigated in 3GPP. In the following, NR in Unlicensed spectrum (NR-U) and a channel access procedure for an unlicensed channel based on Listen Before Talk (LBT) is discussed.

[0007] In order to tackle the ever-increasing demand for data, NR is supported on both licensed spectrum and unlicensed spectrum. Compared to the Long Term Evolution (LTE) LAA, NR-U supports Dual Connectivity (DC) and standalone scenarios, where the Medium Access Control (MAC) procedures including Random Access Channel (RACH) and scheduling procedure on unlicensed spectrum are subject to the LBT failures, while there was no such restriction in LTE LAA since there is licensed spectrum in the LTE LAA scenario so the RACH and scheduling related signaling can be transmitted on the licensed spectrum instead of unlicensed spectrum.

[0008] For Discovery Reference Signal (DRS) transmission such as Primary Synchronization Signal (PSS)ZSecondary Synchronization Signal (SSS), Physical Broadcast Channel (PBCH), and Channel State Information (CSI) Reference Signal (CSI-RS), control channel transmission such as Physical Uplink Control Channel (PUCCH)ZPhysical Downlink Control Channel (PDCCH), physical data channel transmission such as Physical Uplink Shared Channel (PUSCH)ZPhysical Downlink Shared Channel (PDSCH), and uplink Sounding Reference Signal (SRS) transmission, channel sensing should be applied to determine the channel availability before the physical signal is transmitted using the channel.

[0009] In general, the Radio Resource Management (RRM) procedures in NR-U would be rather similar to those in LTE LAA, since NR-U is aiming to reuse LTE LAA / enhanced LAA (eLAA)Zfurther enhanced LAA (feLAA) technologies as much as possible to handle the coexistence between NR-U and other legacy Radio Access Technologies (RATs). RRM measurements and reporting include a special configuration procedure with respect channel sensing and channel availability.

[0010] Channel access / selection for LTE LAA was one of important aspects for co-existence with other RATs such as Wi-Fi. For instance, LTE LAA has aimed to use carriers that are congested with Wi-Fi. In licensed spectrum, a User Equipment (UE) measures Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the downlink radio channel (e.g., Synchronization Signal Block (SSB), CSI-RS) and provides measurement reports to its serving evolved Node B (eNB)Znext generation Node B (gNB). However, the RSRP and RSRQ measurements do not reflect the interference strength on the carrier. Another metric (i.e., Received Signal Strength Indicator (RSSI)) can serve for such purpose. At the eNB / gNB side, it is possible to derive RSSI based on the received RSRP and RSRQ reports; however, this requires that the RSRP and RSRQ reports must be available. Due to Listen Before Talk (LBT) failure in unlicensed spectrum, some reports in terms of RSRP or RSRP may be blocked. This blocking can be due to either the reference signal transmission (DRS) being blocked by LBT failure in the downlink or the measurement report being blocked by LBT failure in the uplink). The measurements in terms of RSSI are very useful. The RSSI measurements together with the time information concerning when and for how long the UEs have made the measurements can assist the gNB / eNB in detecting a hidden node. Additionally, the gNB / eNB can measure the load situation of the carrier, which is useful for the network to prioritize some channels for load balancing and channel access failure avoidance purposes.

[0011] LTE LAA supports measurements of averaged RSSI and channel occupancy for measurement reports. The channel occupancy is defined as percentage of time that RSSI was measured above a configured threshold. Lor this purpose, a RSSI Measurement Timing Configuration (RMTC) includes a measurement duration (e.g., 1-5 milliseconds (ms)) and a period between measurements (e.g., {40, 80, 160, 320, 640} ms).

[0012] Dynamic Channel Occupancy by Load Based Equipment (LBE)

[0013] The 3GPP Release 16 Work Item (WI) for NR-U specifies a dynamic channel access mechanism for an LBE type device. This procedure is designed to randomize the start of transmissions from different nodes that want to access the channel at the same time. This procedure is commonly known as category 4 (CAT4) LBT. The detailed procedure for category 4 LBT (also referred to as Type 1 channel access in 3GPP Technical Specification (TS) 37.213 V 17.0.0 ) is described as shown in the following excerpt from 3GPP TS 37.213:

[0014] ***** START EXCERPT PROM TS 37.213 *****

[0015] A UE may transmit the transmission using Type 1 channel access procedure after first sensing the channel to be idle during the slot durations of a defer duration Td, and after the counter N is zero in step 4. The counter N is adjusted by sensing the channel for additional slot duration(s) according to the steps described below.

[0016] 1) set N = Ninit, where Ninitis a random number uniformly distributed between 0 and CWp, and go to step 4;

[0017] 2) if TV > 0 and the UE chooses to decrement the counter, set IV = IV — 1;

[0018] 3) sense the channel for an additional slot duration, and if the additional slot duration is idle, go to step 4; else, go to step 5; 4) if TV = 0, stop; else, go to step 2.

[0019] 5) sense the channel until either a busy slot is detected within an additional defer duration Tdor all the slots of the additional defer duration Tdare detected to be idle;

[0020] 6) if the channel is sensed to be idle during all the slot durations of the additional defer duration Td, go to step 4; else, go to step 5;

[0021] If a UE has not transmitted a UL transmission on a channel on which UL transmission(s) are performed after step 4 in the procedure above, the UE may transmit a transmission on the channel, if the channel is sensed to be idle at least in a sensing slot duration Tstwhen the UE is ready to transmit the transmission and if the channel has been sensed to be idle during all the slot durations of a defer duration Tdimmediately before the transmission. If the channel has not been sensed to be idle in a sensing slot duration TsLwhen the UE first senses the channel after it is ready to transmit, or if the channel has not been sensed to be idle during any of the sensing slot durations of a defer duration Tdimmediately before the intended transmission, the UE proceeds to step 1 after sensing the channel to be idle during the slot durations of a defer duration Td.

[0022] The defer duration Tdconsists of duration Tf = 16us immediately followed by mpconsecutive slot durations where each slot duration is TsL= 9us, and Tf includes an idle slot duration TsLat start of T . < CIVp < CHp-jais the contention window. CWpadjustment is described in clause 4.2.2. aiqd CWmax pare chosen before step 1 of the procedure above. mp, CWmin p, and CWmax pare based on a channel access priority class p as shown in Table 4.2.1-1, that is signalled to the UE.

[0023] ***** END EXCERPT FROM TS 37.213 *****

[0024] Table 1 / Table 4.2.1-1: Channel Access Priority Class (CAPC) for Uplink from 3GPP TS 37.213 v

[0025] 17.0.0

[0026] Semi-Static Channel Occupancy by Frame Based Equipment (FBE)

[0027] The semi-static channel occupancy allows a FBE to perform a clear channel assessment per fixed frame period for a duration of single 9 microsecond (ps) observation slot. If the channel is found to be busy after Clear Channel Assessment (CCA) operation, the equipment shall not transmit during this fixed frame period. The fixed frame period can be set to a value between 1 ms and 10 ms and can be adjusted once every 200 ms. If the channel is found to be idle, the equipment can transmit immediately up to a duration referred to as channel occupancy time, after which the equipment shall remain silent for at least 5% of said channel occupancy time. At the end of the required idle period, the equipment can resume CCA for channel access. An example of the FBE based channel occupancy operation is shown in Figure 1.

[0028] The semi-static channel occupancy generally has difficulty competing with devices that use dynamic channel occupancy (such as LTE LAA or NR-U) for channel access. A dynamic channel occupancy device has the flexibility to access the channel at any time after a successful LBT procedure, while the semi-static channel occupancy device has one chance for grabbing the channel every fixed frame period. The problem becomes more exacerbated with a longer fixed frame period and higher traffic load. Secondly, the frame based LBT can be rather inflexible for coordinating channel access between networks. If all the nodes are synchronized, then all nodes will find the channel available and transmit simultaneously and cause interference. If the nodes are not synchronized, then some nodes may have definite advantages in getting access to the channel over some other nodes. Nonetheless, semi-static channel occupancy can be a good choice for controlled environments, where a network owner can guarantee absence of dynamic channel occupancy devices and is in control of the behavior of all devices competing to access the channel. In fact, in such deployment, semi-static channel occupancy is an attractive solution because access latencies can be reduced to the minimum and lower complexity is required for channel access due to lack of necessity to perform random backoff.

[0029] It has been identified that FBE operation for the scenario where it is guaranteed that LBE nodes are absent on a long-term basis (e.g., by level of regulation) and FBE gNBs are synchronized can achieve the following:

[0030] • Ability to use frequency reuse factor 1 ;

[0031] • Lower complexity for channel access due to lack of necessity to perform random backoff. In order to deploy a single operator FBE system, the gNBs need to be time aligned. All gNBs will perform the one-shot 9 ps LBT at the same time. If the gNB indicates FBE operation, for an indication of LBT type of Cat2 25 ps or Cat4, the UE follows the mechanism whereby one 9 ps slot is measured within a 25 ps interval.

[0032] The Fixed Frame Period (FFP) is restricted to values of { 1ms, 2ms, 2.5ms, 4ms, 5ms, 10ms}, including the idle period. The starting positions of the FFPs within every two radio frames starts from an even radio frame and are given by i*P where i={0, 1,.., 20 / P-l} where P is the fixed frame period in ms.

[0033] The idle period for a given Subcarrier Spacing (SCS) is equal to ceil(Minimum idle period allowed by regulations / Ts) where the minimum idle period allowed is max(5% of FFP, 100 ps) and Ts is the symbol duration for the given SCS.

[0034] For FBE, channel sensing is performed at fixed time instants. If the channel is determined busy, the base station adopts a fixed back-off and perform LBT again after the fixed backoff. For LBE, channel sensing can be performed at any time instance, and random back-off is adopted when the channel is determined to be busy.

[0035] As described in 3GPP Technical Report (TR) 38.889, it has been identified that FBE operation for the scenario where it is guaranteed that LBE nodes are absent on a long term basis (e.g., by level of regulation) and FBE gNBs are synchronized can achieve the following: Ability to use frequency reuse factor 1 ; Lower complexity for channel access due to lack of necessity to perform random backoff. It is noted that this does not imply that LBE does not have benefits in similar scenarios although there are differences between the two modes of operation. It is also noted that FBE may also have some disadvantages compared to other modes of operation such as LBE, e.g., a fixed overhead for idle time during a frame.

[0036] In NR Release 16, only gNB Channel Occupancy Time (COT) sharing is supported in case of semi-static channel access by FBE. A UE may transmit uplink transmission burst(s) after downlink transmission within a gNB initiated COT. UE transmissions within a fixed frame period can occur if downlink transmission for the serving gNB within the fixed frame period are detected. The detection of any downlink transmission confirms that the gNB has initiated the COT. For this to work, the UE should be aware of the start and end of every FFP cycle. Such UE behaviors are not optimum for Ultra-Reliable Low-Latency Communication (URLLC) like services which require critical latency requirements. UE initiated COT by FBE would be a complementary solution for URLLC.

[0037] Summary

[0038] Systems and methods for measurement reporting in a cellular communications system are disclosed. In one embodiment, a method performed by a User Equipment (UE) comprises generating a measurement report for a target cell, the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell for the target cell. The method further comprises transmitting the measurement report to a Radio Access Network (RAN) node that operates the target cell. In this manner, power saving and reduced time delay in measurement reporting can be provided, e.g., in a cell subject to Clear Channel Assessment (CCA).

[0039] In one embodiment, the target cell is subject to CCA.

[0040] In one embodiment, generating the measurement report for the target cell is responsive to there being a need to obtain measurements on the reference cell for use for measurement reporting for the target cell due to CCA failure on the target cell. In one embodiment, the method further comprises determining that there is a need to obtain measurements on the reference cell for use for measurement reporting for the target cell due to CCA failure on the target cell. In one embodiment, the need to obtain measurements on a reference cell for use for measurement reporting for the target cell due to CCA failure on the target cell is determined based on one or more first criteria are satisfied. In one embodiment, the one or more first criteria comprise a criterion that the UE does not detect any downlink reference signal or any one of a defined set of downlink reference signals in the target cell during a time interval that is longer than a predefined or configured time interval threshold. In one embodiment, the one or more first criteria comprise a criterion that the UE detects one or more signals in the target cell but a corresponding measured value on the one or more detected signals is less than a predefined or configured threshold measurement value in a time interval longer than a predefined or configured time interval threshold. In one embodiment, the one or more first criteria comprise a criterion that the UE detects samples of one or more signals in the target cell but cannot complete a full measurement in a time interval longer than a predefined or configured time interval threshold. In one embodiment, the time interval begins at a time at which the UE last successfully detected and measured a downlink reference signal or one of a defined set of downlink reference signals in the target cell.

[0041] In one embodiment, the method further comprises identifying the reference cell for the target cell. In one embodiment, identifying the reference cell for the target cell comprises identifying the reference cell for the target cell based on one or more second criteria. In one embodiment, the one or more second criteria comprise a criterion that a measured power for a downlink reference signal in the reference cell is higher than a predefined or configured power threshold. In one embodiment, the one or more second criteria comprise a criterion that a measured power for a downlink reference signal in the reference cell is higher than a predefined or configured power threshold, at least no earlier than a predefined or configured time interval threshold before the UE enables measurement reporting for the target cell including measurements, or adjusted versions of the measurements, from a reference cell. In one embodiment, the one or more second criteria comprise a criterion that a last valid spatial relation of the UE with respect to the target cell is the same or sufficiently similar to a spatial relation of the UE relative to the reference cell. In one embodiment, the one or more second criteria comprise a criterion that a last valid spatial relation of the UE with respect to the target cell is the same or sufficiently similar to a spatial relation of the UE relative to the reference cell, at least no earlier than a predefined or configured time interval threshold before the UE enables measurement reporting for the target cell including measurements, or adjusted versions of the measurements, from a reference cell. In one embodiment, the one or more second criteria comprise a criterion that a last valid timing or Doppler characteristic detected by the UE with respect to the target cell is the same as or sufficiently similar to that of the reference cell. In one embodiment, the one or more second criteria comprise a criterion that a last valid timing or Doppler characteristic detected by the UE with respect to the target cell is the same as or sufficiently similar to that of the reference cell, no earlier than a predefined or configured time interval before the UE enables measurement reporting for the target cell including measurements, or adjusted versions of the measurements, from a reference cell. In one embodiment, the one or more second criteria comprise a criterion that a difference between a last valid power measurement of a reference signal on the target cell performed by the UE and that of the reference cell is less than a predefined or configured threshold and both are higher than a power threshold. In one embodiment, the one or more second criteria comprise a criterion that a difference between a last valid power measurement of a reference signal on the target cell performed by the UE and that of the reference cell is less than a predefined or configured threshold and both are higher than a power threshold, no earlier than a predefined or configured time interval before the UE enables measurement reporting for the target cell including measurements, or adjusted versions of the measurements, from a reference cell.

[0042] In one embodiment, the method further comprises transmitting, to the RAN node, an indication that the measurement report comprises one or more measurements that are based on one or more measurements performed on the reference cell.

[0043] In one embodiment, the target cell operates on a carrier in an unlicensed frequency band, and the reference cell operates on a carrier in a licensed frequency band.

[0044] Corresponding embodiment of a UE are also disclosed. In one embodiment, a UE is adapted to generate a measurement report for a target cell, the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell for the target cell. The UE is further adapted to transmit the measurement report to a Radio Access Network (RAN) node that operates the target cell.

[0045] In one embodiment, a UE comprises one or more transmitters, one or more receivers, and processing circuitry associated with the one or more transmitters and the one or more receivers. The processing circuitry is configured to cause the UE to generate a measurement report for a target cell, the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell for the target cell. The processing circuitry is further configured to cause the UE to transmit the measurement report to a RAN node that operates the target cell.

[0046] Embodiments of a method performed by a RAN node are also disclosed. In one embodiment, a method performed by a RAN node comprises obtaining one or more measurements for a UE on a target cell using one or more measurements of the UE on a reference cell for the target cell and / or one or more measurements of a reference UE on the target cell and using the one or more measurements obtained for the UE on the target cell for one or more operations.

[0047] Corresponding embodiments of a RAN node are also disclosed. In one embodiment, a RAN node is adapted to obtain one or more measurements for a UE on a target cell using one or more measurements of the UE on a reference cell for the target cell and / or one or more measurements of a reference UE on the target cell. The RAN node is further adapted to use the one or more measurements obtained for the UE on the target cell for one or more operations.

[0048] In one embodiment, a RAN node comprises processing circuitry and memory storing instructions executable by the processing circuitry whereby the RAN node is operable to obtain one or more measurements for a UE on a target cell using one or more measurements of the UE on a reference cell for the target cell and / or one or more measurements of a reference UE on the target cell and use the one or more measurements obtained for the UE on the target cell for one or more operations.

[0049] Brief Description of the Drawings

[0050] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0051] Figure 1 illustrates an example of Frame-Based Equipment (FBE) based channel occupancy operation;

[0052] Figures 2A and 2B illustrate examples of a cellular communications system in which embodiments of the present disclosure may be implemented;

[0053] Figure 3 is a flow chart that illustrates the operation of a User Equipment (UE) to use measurements on a reference cell for measurement reporting in a target cell in the case of Clear Channel Access (CCA)ZListen Before Talk (LBT) failure in the target cell, in accordance with one embodiment of the present disclosure;

[0054] Figure 4 illustrates a procedure in which a UE uses measurements on a reference cell for measurement reporting in a target cell in the case of CCA / LBT failure in the target cell, in accordance with one embodiment of the present disclosure;

[0055] Figure 5 is a flow chart that illustrates the operation of a Radio Access Network (RAN) node to use measurements on a UE in a reference cell or measurements on a reference UE in a target cell as a baseline for measurements for the UE in the target cell in the case of CCA / LBT failure in the target cell, in accordance with one embodiment of the present disclosure

[0056] Figure 6 is a schematic block diagram of a RAN node according to some embodiments of the present disclosure;

[0057] Figure 7 is a schematic block diagram that illustrates a virtualized embodiment of the RAN node of Figure 6 according to some embodiments of the present disclosure;

[0058] Figure 8 is a schematic block diagram of the RAN node of Figure 6 according to some other embodiments of the present disclosure;

[0059] Figure 9 is a schematic block diagram of a UE according to some embodiments of the present disclosure;

[0060] Figure 10 is a schematic block diagram of the UE of Figure 9 according to some other embodiments of the present disclosure; Figure 11 illustrates a telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments of the present disclosure;

[0061] Figure 12 is a generalized block diagram of a host computer communicating via a base station with a UE over a partially wireless connection in accordance with some embodiments of the present disclosure;

[0062] Figure 13 is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure;

[0063] Figure 14 is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure;

[0064] Figure 15 is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure; and

[0065] Figure 16 is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure.

[0066] Detailed Description

[0067] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0068] Radio Node: As used herein, a “radio node” is either a radio access node or a wireless communication device.

[0069] Radio Access Node or Radio Access Network (RAN) Node: As used herein, a “radio access node” or “RAN node” is any node in a RAN of a cellular communications network that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.

[0070] Wireless Communication Device or User Equipment (UE): As used herein, a “wireless communication device” or “UE” is any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device or UE include, but are not limited to: a UE in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (loT) device. Such wireless communication devices or UEs may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device or UE may be a portable, hand-held, computer-comprised, or vehicle -mounted mobile device, enabled to communicate voice and / or data via a wireless connection.

[0071] Network Node: As used herein, a “network node” is any node that is either part of the RAN or the core network of a cellular communications network / system.

[0072] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0073] Note that, in the description herein, reference may be made to the term “cell”; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0074] Existing solutions for NR in Unlicensed spectrum (NR-U) have a number of challenges. For a UE which only operates in one unlicensed cell on one frequency layer, the existing Clear Channel Access (CCA) mechanism is applicable. Since more and more UEs are now supporting the capability to operate in more than one cell consisting of a one or more unlicensed cells or a combination of one or more licensed cell and one or more unlicensed cell, how to address CCA in this kind of UE more efficiently is a new issue. In this case, the UE may experience LBT failures in an unlicensed cell such that the UE’s downlink measurements on signal(s) (e.g., SSB, CSI-RS) from a gNB(s) would be subject to the LBT failure. Similarly, the gNB’s uplink measurements on a signal(s) from a UE in an unlicensed cell may also be subject to LBT failure. Due to missing or insufficient measurement results, the UE and the gNB may suffer from degradation of Quality of Service (QoS) in subsequent transmissions or receptions.

[0075] Systems and methods are disclosed herein that address the aforementioned and / or other challenges. Systems and methods are disclosed herein that enable a UE to report measurements including measurements performed on a signal(s) from a reference cell or adjusted versions thereof in a measurement report for a target cell for which CCA is mandatorily applied when there is a CCA failure(s) on the target cell (e.g., a CCA failure(s) that prevents the UE from performing at least some related measurements on the targe cell). Notably, the UE supports operation in more than one cell including a cell(s) that require CCA operation (e.g., a cell(s) in unlicensed spectrum) and a cell(s) that do not require CCA operation (e.g., a cell(s) in licensed spectrum).

[0076] According to one embodiment, UE takes the measurement report(s) on reference signal(s) in other cell(s) than one unlicensed cell as baseline of reporting of reference signal(s) in the unlicensed cell provided network node configures CCA and UE doesn’t detect reference signal(s) in the unlicensed cell.

[0077] In one particular example, UE uses measurement report(s) on reference signal(s) in other cell(s) than one unlicensed cell as reporting of reference signal(s) in the unlicensed cell.

[0078] According to one of aspects in the embodiment, UE follows one or more than one rule to enable the above embodiment with respect to corresponding criteria and some examples further are provided. According to another of aspects in the embodiment, UE notices network node that the current reporting in the unlicensed cell is based on reference signal(s) in other cell(s) than the unlicensed cell.

[0079] From network perspective, network node determines the application of the embodiment and signals message to UE to allow UE to adopt the embodiment through dedicated signaling, e.g. RRC, MAC-CE or DCI.

[0080] The solution provides a method for the UE in more cells than only one unlicensed cell to adaptively enable and adjust reporting based on introduced rules.

[0081] Embodiments of the present disclosure may provide a number of advantages over existing solutions. The solution can engage power saving and reduce time delay in measurement reporting in unlicensed cell to facilitate network node operation in turn based on reporting.

[0082] Embodiments of the present disclosure relate to the following scenario. The carrier on which the clear channel assessment (CCA) is applied may belong to a shared spectrum or an unlicensed band or band with contention-based access etc. The CCA (also referred to as Listen-Before Talk (LBT)) based operation is more generally called contention-based operation. The transmission of signals on a carrier subjected to CCA is also called contention-based transmission. The contention-based operation is typically used for transmission on carriers of unlicensed frequency band. But this mechanism may also be applied for operating on carriers belonging to licensed band for example to reduce interference. The transmission of signals on a carrier which is not subjected to CCA is also called contention free transmission. CCA procedure can be performed by UE prior to a transmission and / or by a network node (e.g., radio access node such as, e.g., a base station) prior to a transmission.

[0083] In addition, both Load-Based Equipment (LBE) based channel access schemes (also referred to herein as dynamic channel access) and Frame-Based Equipment (FBE) based channel access schemes (also referred to herein as semi static channel access) are covered in the following embodiments.

[0084] Measurements on a signal or radio signal used herein can be any physical signal or physical channel. Examples of downlink physical signals are reference signals (RS) such as Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), Channel State Information (CSI) Reference Signal (CSI-RS), Demodulation Reference Signal (DMRS) in Synchronization Signal (SS)ZPhysical Broadcast Channel (PBCH) Block (SSB), Discovery Reference Signal (DRS), Cell-specific Reference Signal (CRS), Positioning Reference Signal (PRS), etc. RS may be periodic (e.g., RS occasion carrying one or more RSs may occur with certain periodicity e.g., 20 ms, 40 ms, etc.) or aperiodic.

[0085] Measurement reports include one or more measurement results at the UE side such as, e.g., CSI, received power level, received Signal to Noise Ratio (SNR), Signal to Interference plus Noise Ratio (SINR), Reference Signal Received Power (RSRP), Reference Signal Receive Quality (RSRQ), or any other evaluation outcome with respect to received signals.

[0086] Embodiments of the present disclosure are applicable to operations of a UE and a network node in one unlicensed cell applying CCA mandatorily when clear channel is invalid provided that the UE supports and operates in more (at least one) cell(s) in addition to the unlicensed cell. Embodiments of the present disclosure can be applied to a UE in Radio Resource Control (RRC) Connected state, RRC Idle state, or RRC Inactive state.

[0087] For sake of simplicity, an unlicensed cell applying CCA mandatorily with an invalid clear channel is referred to herein as a “target cell” or “Cell_targef On the other hand, the aforementioned at least one cell in addition to the unlicensed cell is referred to herein as a “reference cell” or “Cell_reference”. The reference cell may be any type of cell such as, e.g.:

[0088] • a licensed cell (i.e., a cell that operates in licensed frequency spectrum),

[0089] • an unlicensed cell with CCA, or

[0090] • an unlicensed cell without CCA.

[0091] Note that, for a cell on an unlicensed carrier, the CCA / LBT operation may not be mandatory. Therefore, CCA / LBT may be enabled or disabled in the cell depending on conditions such as, e.g., cell load, interference / congestion situation for the cell, etc.

[0092] In the description herein, a cell is considered to have “invalid clear channel for a UE” when the UE has recently experienced LBT / CCA failure for that cell such that the UE’s downlink measurement(s) is subject to CCA / LBT failure or uplink transmission(s) on the cell is subject to CCA / LBT failure. Similarly, a cell is considered to have “invalid clear channel for the gNB towards a UE” when the gNB has recently experienced CCA / LBT failure such that the gNB’s uplink measurement(s) is subject to CCA / LBT failure or downlink transmission(s) towards the UE is subject to CCA / LBT failure.

[0093] In the below embodiments, a UE or the gNB may be aware of occurrence of CCA / LBT failure via at least one of the following alternatives:

[0094] • Alternative 1 : The UE or the gNB performs LBT operations (which do not need to depend on whether the UE or the gNB need to do transmission prior to LBT operations). Based on the performed LBT operations, the UE or the gNB estimates whether / how many LBT failure instances are being detected within a time period. Alternatively, a CCA / LBT failure is determined to have occurred when the detected number or the percentage of LBT failures is not lower than a predefined or configured threshold.

[0095] • Alternative 2: The UE may signal the gNB of detection of LBT failures by the UE such that the gNB can determine that its recent uplink measurements or reception from the UE may be subject to LBT failures. The gNB may signal the UE of detection of LBT failures by the gNB such that the UE can determine that its recent downlink measurements or reception from the gNB may be subject to LBT failures. The UE or the gNB determine that there is a CCA / LBT failure when f the number or the percentage of LBT failures is not lower than a predefined or configured threshold. The target cell and the reference cell may be operated under the same or different radio access nodes (e.g., the same or different gNBs). Furthermore, the target cell and the reference cell may be operated in the same network or different networks (e.g., in the same Public Land Mobile Network (PLMN) or different PLMNs). A special example is where the target cell and the reference cell are operated in networks belonging to different network operators. Figures 2A and 2B illustrate examples of a cellular communications system 200 in which embodiments of the present disclosure may be implemented. More specifically, Figure 2A illustrates an embodiment of the cellular communications system 200 in which a RAN node 202 operates two cells, which for the embodiments described herein are referred to as a target cell 204-T and a reference cell 204- R. A UE 206 is served by or is otherwise enabled to transmit and receive signals on both the target cell 204-T and the reference cell 204-R using a technology such as, e.g., carrier aggregation or dual connectivity. For the embodiments described herein, the target cell 204-T is a cell for which CCA / LBT is required. In one specific example, the target cell 204-T is an unlicensed cell (i.e., a cell that operates on a carrier in an unlicensed frequency spectrum). The reference cell 204-T is either a cell that does not require CCA / LBT (e.g., a licensed cell or cell that operates on a carrier in a licensed frequency spectrum) or a cell that requires CCA / LBT either always or under certain conditions. It should further be noted that the target cell 204-T and the reference cell 204-R may be in the same network (e.g., the same Public Land Mobile Network (PLMN)) or in different networks (e.g., different PLMNs), which may be operated by different network operators. In one embodiment, the RAN node 202 is a gNB, and the cells 204-T and 204-R are NR cells (e.g., the target cell 204-T may be a NR-U cell and the reference cell 204-R may be a NR cell in licensed spectrum); however, the embodiments described herein are not limited thereto and can be utilized in any type of cellular communication system (e.g., a 4G, 5G, or 6G system).

[0096] Figure 2B illustrates another embodiment of the cellular communications system 200 that is similar to that of Figure 2A but where the target cell 204-T is operated by a first, or target, RAN node 202-T and the reference cell 204-R is operated by a second, or reference, RAN node 202-R. Otherwise, the embodiment of Figure 2B is the same as that of Figure 2A. As such, the details above about Figure 2A are not repeated here in the description of Figure 2B, but one should understand that those details are equally applicable to Figure 2B.

[0097] Figure 3 is a flow chart that illustrates the operation of the UE 206 in accordance with one embodiment of the present disclosure. Optional steps are represented by dashed lines / boxes. Again, the UE 206 is capable of operating in both the target cell 204-T and the reference cell 204-R, where CCA is applied in the target cell 204-T. As illustrated, the UE 206 determines that there is a need to obtain measurements on a reference for use in providing a measurement report for the target cell 204-T (e.g., due to CCA / LBT failure in the target cell 204-T) (step 300). More specifically, in one embodiment, the UE 206 determines whether one or more signals (e.g., one or more downlink reference signals) in the target cell 204-T satisfies one or more criteria to using measurements on the reference cell 204-R. In one embodiment, the one or more criteria include one or more of the following:

[0098] • In one example, the one or more criteria include a criterion that the UE 206 does not detect any downlink reference signal (or any one of a defined set of downlink reference signals) in the target cell 204-T during a time interval that is longer than a predefined or configured time interval threshold (TTH T1). In one embodiment, this time interval begins at a time at which the UE 206 last successfully detected and measured a downlink reference signal (or one of a defined set of downlink reference signals) in the target cell 204-T.

[0099] • In another example, the one or more criteria include a criterion that the UE 206 detects one or more signals (e.g., one or more downlink reference signals such as, e.g., one or more of a defined set of reference signals) in the target cell 204-T but a corresponding measured value on the detected signal(s) (e.g., a measured RSRP value) is less than a predefined or configured threshold measurement value (e.g., a predefined or configured power threshold or RSRP threshold)

[0100] (PTH T1) in a time interval longer than a predefined or configured time interval threshold (TTH T2). In one embodiment, this time interval begins at a time at which the UE 206 last successfully detected and measured a downlink reference signal (or one of a defined set of downlink reference signals) in the target cell 204-T.

[0101] • In another example, the one or more criteria include a criterion that the UE 206 detects samples of signals (e.g., one or more downlink reference signals or one or more of a defined set of downlink reference signals) in the target cell 204-T but cannot complete a full measurement in a time interval longer than a predefined or configured time interval threshold (TTH T3). In one embodiment, this time interval begins at a time at which the UE 206 last successfully detected and measured a downlink reference signal (or one of a defined set of downlink reference signals) in the target cell 204-T.

[0102] The UE 206 identifies, or selects, a suitable reference cell (e.g., the reference cell 204-R) for the target cell 204-T (step 302). In this example, the reference cell 204-R is identified a suitable reference cell for the target cell 204-T. A “suitable reference cell” is a cell that satisfies one or more criteria for serving as a reference cell for which measurements on the reference cell can serve as (or adjusted versions of such measurements can serve as) measurements on the target cell 204-T. In one embodiment, the one or more criteria for serving as a reference cell include one or criteria related to the reference cell and the target cell 204-T. Some examples of the one or more criteria for serving as a reference cell for the target cell 204-T are as follows:

[0103] • In one example, the one or more criteria for serving as a reference cell include a criterion that a measured RSRP for a downlink reference signal in the reference cell is higher than a predefined or configured power threshold (PTH R1).

[0104] • In one example, the one or more criteria for serving as a reference cell include a criterion that a measured RSRP for a downlink reference signal in the reference cell is higher than a predefined or configured power threshold (PTH R1), at least no earlier than a predefined or configured time interval threshold (TTH R1) before the UE 206 enables measurement reporting for the target cell 204-T including measurements (or modified versions of the measurements) from a reference cell.

[0105] • In another example, the one or more criteria for serving as a reference cell for the target cell 204- T include a criterion that a spatial relation of the UE 206 with respect to the target cell 204-T before the invalid clear channel status for the target cell 204-T (i.e., the last valid spatial relation of the UE 206 with respect to the target cell 204-T) is the same or sufficiently similar to (e.g., matches to at least a predefined or configured threshold degree) the spatial relation of the UE 206 relative to the reference cell, at least no earlier than a predefined or configured time interval threshold (TTH_R2) before the UE 206 enables measurement reporting for the target cell 204-T including measurements (or modified versions of the measurements) from a reference cell. o In an example, the spatial relations for two cells are same or sufficiently similar in term of channel conditions such as, e.g., Doppler Shift, Doppler Spread, Average Delay, Delay Spread, Spatial Receive (Rx) Parameter(s), and / or the like, or any combination thereof. o In another example, the spatial relations for two cells are the same or sufficiently similar if properties of the channel over which a symbol in one cell is conveyed can be inferred from the channel over which a symbol on the other cell is conveyed.

[0106] • In another example, the one or more criteria for serving as a reference cell for the target cell 204- T include a criterion that the UE 206 detected timing / Doppler characteristics with respect to the target cell 204-T before invalid clear channel status (i.e. the last valid timing / Doppler characteristics) is the same as or sufficiently similar to (e.g., matches to a predefined or configured threshold degree) that of the reference cell, no earlier than a predefined or configured time interval (TTH_R4) before the UE 206 enables measurement reporting for the target cell 204- T including measurements (or modified versions of the measurements) from a reference cell.

[0107] • In another example, one or more criteria for serving as a reference cell for the target cell 204-T include a criterion that the UE measured RSRP of a reference signal from the target cell 204-T before invalid clear channel status (i.e., the last valid RSRP) is close to that of the reference cell (the difference is less than a predefined or configured threshold (P deltal)) and both are higher than a power threshold (PTH R4), no earlier than a predefined or configured time interval (TTH_R5) before the UE 206 enables measurement reporting for the target cell 204-T including measurements (or modified versions of the measurements) from a reference cell.

[0108] Note that, in order for the UE 206 to enable measurement reporting in the target cell 204-T using measurement s) in the reference cell 204-R, the criteria of step 300 must be satisfied and a reference cell (i.e., the reference cell 204-R in this example) satisfying the criteria of step 302 must be fulfilled.

[0109] The UE 206 then (e.g., in response to the determining of step 300 and / or the identifying of step 302) generates a measurement report for the target cell 204-T and transmits the measurement report on the target cell 204-T, using one or more measurements performed on the reference cell 204-R (step 304). In one embodiment, the measurement(s) performed on the reference cell 204-R serve as a baseline of measurement reporting in the target cell 204-T. In one embodiment, the one or more measurements performed on the reference cell 204-R that are used for the measurement report in the target cell 204-T include any one or more of the following: one or more layer 3 (L3) measurements, one or more layer 1 (LI) measurements, or one or more measurements related to CSI reporting such as, e.g., one or more RSRP measurements, one or more RSRQ measurements, a CQI, a PMI, a RI, a CRI, and / or an i 1 derived by the UE 206 based on a measurement(s) on one or more downlink reference signal(s) on the reference cell 204-R. In one embodiment, the measurement(s) performed on the reference cell 204-R are directly used as measurements for the target cell 204-T and included in the measurement report for the target cell 204-T. In another embodiment, the UE 206 applies a predefined, configured, or determined (by the UE 206) offset(s) to the measurement(s) performed on the reference cell 204-R to provide an adjusted measurement(s) that is included in the measurement report for the target cell 204-T. The offset applied may depend on the type of measurement and / or a frequency band of the reference cell 204-R and / or a frequency band of the target cell 204-T. In one example, the UE 206 determines the offset(s) to be applied based on historical measurements in the target cell 204-T (when clear channel was valid / passed) and those in the reference cell 204-R. In one example, after measurements in Cell_reference and Cell_target sperately, it is determined by the UE that measurements in RSRP measured in Cell target is {RSRP measured CelUtarget }, then, in a time interval threshold (e.g. 60 seconds) and CelUtarget falls into invalid clear channel status, RSRP to be reported for Cell target is {RSRP measured Cell reference +P_delta2}.

[0110] In one embodiment, the UE 206 signals an indication to the network node (e.g., gNB) to which the measurement report is transmitted that indicates whether a measurement included in the measurement report is based on a measurement(s) performed on the reference cell 204-R or is a measurement performed on the target cell 204-T (e.g., in the conventional manner). In one embodiment, this indication is signaled to the network node prior to the transmission of the measurement report. In another embodiment, this indication is signaled to the network node after the transmission of the measurement report. In another embodiment, this indication is signaled to the network node in the measurement report, e.g., as a new filed or parameter in the measurement report. The indication may be signaled to the network node via any suitable signaling mechanism such as, e.g., RRC signaling, Medium Access Control (MAC) Control Element (CE), or LI signaling carried in a physical channel such as, e.g., PRACH, PUCCH, or PUSCH. In another embodiment, the signaling of the indication is provided by using a particular set of PRACH resources, PUCCH resources, or PUSCH resources (e.g., one set of resources indicates that a measurement(s) included in the report is based on a measurement in the reference cell 204-R and another set of resources indicates conventional measurement). In one embodiment, in addition to the indication, the UE 206 may further provide an index or identity of the reference cell 204-R, an index or identity of the target cell 204-T, an indication of a time period during which the indication is valid, and / or an identity of the UE 206.

[0111] From network node perspective, network node determines the application of the introduced reporting mechanism with respect to 3GPP compatible or non-3GPP methods and signals message (applicable or inapplicable) to the UE 206.

[0112] In one example, the UE 206 determines the reference cell 204-R which can be used in the introduced reporting mechanism, e.g., if there are more than one cell configured and operated by network node. In one of the examples, the UE 206 selects the best suitable reference cell 204-R if multiple suitable reference cells are found. In one option, the UE 206 selects a reference cell randomly from the set of suitable reference cells. In one option, the UE 206 selects the reference cell with strongest downlink radio channel quality. In one option, the UE 206 selects a reference cell which has not been used recently (e.g., within a predefined or configured amount of time) or the reference cell least recently used.

[0113] In one embodiment, after receiving reporting by the UE 206 in the target cell 204-T, the network uses the reporting as prerequisite of a next transmission to configure proper transmission configurations or operations, e.g. beam management, mobility etc.

[0114] Figure 4 illustrates a procedure in accordance with one embodiment of the present disclosure. Optional steps are represented by dashed lines / boxes. As illustrated, the RAN node 202-T (Figure 2A) or 202 (Figure 2B) performs a CCA and determines that the channel for downlink transmission on the target cell 204-T is clear (i.e., determines that there is a valid CCA) (step 400) and transmits a downlink reference signal on the target cell 204-T (step 402). The RAN node 202-R (Figure 2A) or 202 (Figure 2B) transmits a downlink reference signal on the reference cell 204-R (step 404). The UE 206 performs measurements on both the downlink reference signal on the target cell 204-T and the downlink reference signal on the refence cell 204-R (step 406).

[0115] The RAN node 202-T / 202 performs another CCA on the target cell 204-T and determines that the channel is not clear (i.e., invalid CCA) (step 408) and, as a result, refrains from transmitting a downlink reference signal on the target cell 204-T (step 410). As a result of the invalid CCA and the reference signal not being transmitted on the target cell 204-T, the UE 206 determines that there is a need to use measurement s) on a reference cell for measurement reporting for the target cell 204-T (step 412). Note that step 412 corresponds to step 300 of Figure 3 and, as such, the details provided above regarding step 300 of Figure 3 are equally applicable here to step 412. In response to the determination made in step 412, the UE 206 evaluates a proximity condition(s) (i.e., identifies a suitable reference cell for the target cell 204-T), as described above with respect to step 302 of Figure 3 (step 414). In this example, the reference cell 204-R is identified, or selected, as the reference cell for the target cell 204-T. Using the measurement s) performed on the reference cell 204-R in step 406 and / or measurement(s) performed on further downlink reference signal(s) (or further instances of the same reference signal(s)) on the reference cell 204-R (step 416), the UE 206 generates and transmits a measurement report on the target cell 204-T using the measurement s) performed on the reference cell 204-R (step 418). Optionally, the UE 206 also transmits an indication that the measurement report includes a measurement(s) that is from or based on (e.g., an adjusted version of) a measurement(s) performed on the reference cell 204-R, as described above (step 420). Once the RAN node 202-T / 202 performs a valid CCA for the target cell 204-T (step 422), the RAN node 202-T / 202 may perform further operation9s) based on the received measurement report (step 424).

[0116] Further embodiments will now be described for a scenario in which a target cell is considered to be with invalid clear channel for the RAN node (e.g., gNB) towards a specific UE. In this case, the RAN node may use uplink measurements on uplink reference signals from the UE in another reference cell as the baseline for uplink measurements for the UE in the target cell. Alternatively, the RAN node (e.g., gNB) may use uplink measurements on reference signals from another UE (e.g., a reference UE) in the target cell as the baseline for uplink measurements for the UE in the target cell. The steps that the RAN node performs would be similar as the steps that the UE may perform in the embodiments described above.

[0117] More specially, Figure 5 is a flow chart that illustrates the operation of a RAN node 202-T / 202 operating the target cell 204-T to use measurements on the UE 206 in the reference cell 204-R or measurements on a reference UE in the target cell 204-T as a baseline for measurements for the UE 206 in the target cell 204-T in the case of CCA / LBT failure in the target cell 204-T, in accordance with one embodiment of the present disclosure. Optional steps are represented by dashed lines / boxes. As illustrated, the RAN node 202-T / 202 determines that there is a need to use measurements for the UE 206 on a reference cell and / or measurements for a reference UE on the target cell 204-T, as measurements for or as a baseline for adjustments to provide measurements for the UE 206 in the target cell 204-T (step 500). This determination may be made on criteria similar to those described above for step 300 of Figure 3 but for the uplink direction rather than the downlink direction. More specifically, in one embodiment, the RAN node 202-T / 202 determines whether one or more signals (e.g., one or more uplink reference signals) in the target cell 204-T from the UE 206 satisfies one or more criteria. In one embodiment, the one or more criteria include one or more of the following:

[0118] • In one example, the one or more criteria include a criterion that the RAN node 202-T / 202 does not detect any uplink reference signal (or any one of a defined set of downlink reference signals) from the UE 206 in the target cell 204-T during a time interval that is longer than a predefined or configured time interval threshold. In one embodiment, this time interval begins at a time at which the RAN node 202-T / 202 last successfully detected and measured an uplink reference signal (or one of a defined set of uplink reference signals) from the UE 206 in the target cell 204- T.

[0119] • In another example, the one or more criteria include a criterion that RAN node 202-T / 202 detects one or more signals (e.g., one or more uplink reference signals such as, e.g., one or more of a defined set of uplink reference signals) from the UE 206 in the target cell 204-T but a corresponding measured value on the detected signal(s) (e.g., a measured RSRP value) is less than a predefined or configured threshold measurement value (e.g., a predefined or configured power threshold or RSRP threshold) in a time interval longer than a predefined or configured time interval threshold. In one embodiment, this time interval begins at a time at which the RAN node 202-T / 202 last successfully detected and measured an uplink reference signal (or one of a defined set of uplink reference signals) from the UE 206 in the target cell 204-T.

[0120] • In another example, the one or more criteria include a criterion that the RAN node 202-T / 202 detects samples of signals (e.g., one or more uplink reference signals or one or more of a defined set of uplink reference signals) from the UE 206 in the target cell 204-T but cannot complete a full measurement in a time interval longer than a predefined or configured time interval threshold.

[0121] In one embodiment, this time interval begins at a time at which the RAN node 202-T / 202 last successfully detected and measured an uplink reference signal (or one of a defined set of uplink reference signals) from the UE 206 in the target cell 204-T.

[0122] In response to the determination made in step 500, the RAN node 202-T / 202 identifies or selects a suitable reference cell for the target cell 204-T and / or a suitable reference UE for the UE 206 in the target cell 204-T, based on one or more predefined or configured criteria (step 502). These criteria may be similar to those described above for step 302 of Figure 300 but from the network or uplink perspective rather than the UE or downlink perspective. A “suitable reference cell” is a cell that satisfies one or more criteria for serving as a reference cell for which measurements on the reference cell can serve as (or adjusted versions of such measurements can serve as) measurements on the target cell 204-T. Likewise, a “suitable reference UE” is a UE that satisfies one or more criteria for serving as a reference UE for which measurements on the target cell 204-T can serve as (or adjusted version of such measurements can serve as) measurements for the UE 206 on the target cell 204-T.

[0123] In one embodiment, the one or more criteria for serving as a reference cell include one or criteria related to the reference cell and the target cell 204-T. Some examples of the one or more criteria for serving as a reference cell for the target cell 204-T are as follows:

[0124] • In one example, the one or more criteria for serving as a reference cell include a criterion that a measured RSRP for an uplink reference signal from the UE 206 in the reference cell is higher than a predefined or configured power threshold.

[0125] • In one example, the one or more criteria for serving as a reference cell include a criterion that a measured RSRP for an uplink reference signal from the UE 206 in the reference cell is higher than a predefined or configured power threshold, at least no earlier than a predefined or configured time interval threshold before the RAN node 202-T / 202 enables use of measurements for the UE 206 (or adjusted versions thereof) on a reference cell as measurements for the UE 206 on the target cell 204-T.

[0126] • In another example, the one or more criteria for serving as a reference cell for the target cell 204- T include a criterion that a spatial relation of the UE 206 with respect to the target cell 204-T before the invalid clear channel status for the target cell 204-T (i.e., the last valid spatial relation of the UE 206 with respect to the target cell 204-T) is the same or sufficiently similar to (e.g., matches to at least a predefined or configured threshold degree) the spatial relation of the UE 206 relative to the reference cell, at least no earlier than a predefined or configured time interval threshold before the RAN node 202-T / 202 enables use of measurements for the UE 206 (or adjusted versions thereof) on a reference cell as measurements for the UE 206 on the target cell 204-T.

[0127] • In another example, the one or more criteria for serving as a reference cell for the target cell 204- T include a criterion that the RAN node 202-T / 202 detected timing / Doppler characteristics for the UE 206 with respect to the target cell 204-T before invalid clear channel status (i.e. the last valid timing / Doppler characteristics) is the same as or sufficiently similar to (e.g., matches to a predefined or configured threshold degree) that of UE 206 with respect to the reference cell, no earlier than a predefined or configured time interval before the RAN node 202-T / 202 enables use of measurements for the UE 206 (or adjusted versions thereof) on a reference cell as measurements for the UE 206 on the target cell 204-T.

[0128] • In another example, one or more criteria for serving as a reference cell for the target cell 204-T include a criterion that the RAN node measured RSRP of a reference signal from the UE 206 on the target cell 204-T before invalid clear channel status (i.e., the last valid RSRP) is close to that of the reference cell (the difference is less than a predefined or configured threshold (P_deltal)) and both are higher than a power threshold, no earlier than a predefined or configured time interval before the RAN node 202-T / 202 enables use of measurements for the UE 206 (or adjusted versions thereof) on a reference cell as measurements for the UE 206 on the target cell 204-T.

[0129] The one or more criteria used to select a suitable reference UE include, for example, any one or any combination of the following:

[0130] • The reference UE has same or similar radio channel quality measurement in the recent measurement periods as the target UE 206. The reference UE has similar radio channel quality measurement as the target UE 206 means that the difference between their radio channel quality measurement is below a threshold.

[0131] • The reference UE has same or similar timing as the target UE 206. In an example, the timing may be measured in terms of DL timing. In another example, the timing may be measured in terms of UL timing. Both UEs have similar timing mean that their timing difference is below a threshold.

[0132] • The reference UE has the same or similar physical distance away from the serving RAN node as the target UE 206. Both UEs have similar physical distances away from the serving RAN node means that the difference between their distances away from the serving RAN node is below a threshold.

[0133] The RAN node 202-T / 202 then obtains (and optionally uses) one or more measurements for the UE 206 for the target cell 204-T, using one or more measurements for the UE 206 in the identified reference cell (e.g., reference cell 204-R in this example) and / or one or more measurements for the identified reference UE in the target cell 204-T (step 504).

[0134] Figure 6 is a schematic block diagram of a RAN node 600 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The RAN node 600 may be, for example, a base station (e.g., gNB) or a network node that implements all or part of the functionality of the base station (e.g., a gNB-DU). The RAN node 600 may be the RAN node 202, the target RAN node 202-T, or the reference RAN node 202-R in the embodiments described above. As illustrated, the RAN node 600 includes a control system 602 that includes one or more processors 604 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and / or the like), memory 606, and a network interface 608. The one or more processors 604 are also referred to herein as processing circuitry. In addition, the RAN node 600 may include one or more radio units 610 that each includes one or more transmitters 612 and one or more receivers 614 coupled to one or more antennas 616. The radio units 610 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 610 is external to the control system 602 and connected to the control system 602 via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) 610 and potentially the antenna(s) 616 are integrated together with the control system 602. The one or more processors 604 operate to provide one or more functions of a RAN node 600 as described herein. In some embodiments, the fimction(s) are implemented in software that is stored, e.g., in the memory 606 and executed by the one or more processors 604.

[0135] Figure 7 is a schematic block diagram that illustrates a virtualized embodiment of the RAN node 600 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. Again, optional features are represented by dashed boxes.

[0136] As used herein, a “virtualized” RAN node is an implementation of the RAN node 600 in which at least a portion of the functionality of the RAN node 600 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the RAN node 600 may include the control system 602 and / or the one or more radio units 610, as described above. The control system 602 may be connected to the radio unit(s) 610 via, for example, an optical cable or the like. The RAN node 600 includes one or more processing nodes 700 coupled to or included as part of a network(s) 702. If present, the control system 602 or the radio unit(s) are connected to the processing node(s) 700 via the network 702. Each processing node 700 includes one or more processors 704 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 706, and a network interface 708.

[0137] In this example, functions 710 of the RAN node 600 described herein are implemented at the one or more processing nodes 700 or distributed across the one or more processing nodes 700 and the control system 602 and / or the radio unit(s) 610 in any desired manner. In some particular embodiments, some or all of the functions 710 of the RAN node 600 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 700. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 700 and the control system 602 is used in order to carry out at least some of the desired functions 710. Notably, in some embodiments, the control system 602 may not be included, in which case the radio unit(s) 610 communicate directly with the processing node(s) 700 via an appropriate network interface(s).

[0138] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of RAN node 600 or a node (e.g., a processing node 700) implementing one or more of the functions 710 of the RAN node 600 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0139] Figure 8 is a schematic block diagram of the RAN node 600 according to some other embodiments of the present disclosure. The RAN node 600 includes one or more modules 800, each of which is implemented in software. The module(s) 800 provide the functionality of the RAN node 600 described herein. This discussion is equally applicable to the processing node 700 of Figure 7 where the modules 800 may be implemented at one of the processing nodes 700 or distributed across multiple processing nodes 700 and / or distributed across the processing node(s) 700 and the control system 602.

[0140] Figure 9 is a schematic block diagram of a UE 900 according to some embodiments of the present disclosure. The UE 900 is, in one embodiment, the UE 206 described above. As illustrated, the UE 900 includes one or more processors 902 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 904, and one or more transceivers 906 each including one or more transmitters 908 and one or more receivers 910 coupled to one or more antennas 912. The transceiver(s) 906 includes radio-front end circuitry connected to the antenna(s) 912 that is configured to condition signals communicated between the antenna(s) 912 and the processor(s) 902, as will be appreciated by on of ordinary skill in the art. The processors 902 are also referred to herein as processing circuitry. The transceivers 906 are also referred to herein as radio circuitry. In some embodiments, the functionality of the UE 900 described above may be fully or partially implemented in software that is, e.g., stored in the memory 904 and executed by the processor(s) 902. Note that the UE 900 may include additional components not illustrated in Figure 9 such as, e.g., one or more user interface components (e.g., an input / output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and / or the like and / or any other components for allowing input of information into the UE 900 and / or allowing output of information from the UE 900), a power supply (e.g., a battery and associated power circuitry), etc.

[0141] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the UE 900 according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0142] Figure 10 is a schematic block diagram of the UE 900 according to some other embodiments of the present disclosure. The UE 900 includes one or more modules 1000, each of which is implemented in software. The module(s) 1000 provide the functionality of the UE 900 described herein.

[0143] With reference to Figure 11, in accordance with an embodiment, a communication system includes a telecommunication network 1100, such as a 3GPP-type cellular network, which comprises an access network 1102, such as a RAN, and a core network 1104. The access network 1102 comprises a plurality of base stations 1106A, 1106B, 1106C, such as Node Bs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area 1108A, 1108B, 1108C. Each base station 1106A, 1106B, 1106C is connectable to the core network 1104 over a wired or wireless connection 1110. A first UE 1112 located in coverage area 1108C is configured to wirelessly connect to, or be paged by, the corresponding base station 1106C. A second UE 1114 in coverage area 1108A is wirelessly connectable to the corresponding base station 1106A. While a plurality of UEs 1112, 1114 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 1106.

[0144] The telecommunication network 1100 is itself connected to a host computer 1116, which may be embodied in the hardware and / or software of a standalone server, a cloud-implemented server, a distributed server, or as processing resources in a server farm. The host computer 1116 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections 1118 and 1120 between the telecommunication network 1100 and the host computer 1116 may extend directly from the core network 1104 to the host computer 1116 or may go via an optional intermediate network 1122. The intermediate network 1122 may be one of, or a combination of more than one of, a public, private, or hosted network; the intermediate network 1122, if any, may be a backbone network or the Internet; in particular, the intermediate network 1122 may comprise two or more sub-networks (not shown).

[0145] The communication system of Figure 11 as a whole enables connectivity between the connected UEs 1112, 1114 and the host computer 1116. The connectivity may be described as an Over-the-Top (OTT) connection 1124. The host computer 1116 and the connected UEs 1112, 1114 are configured to communicate data and / or signaling via the OTT connection 1124, using the access network 1102, the core network 1104, any intermediate network 1122, and possible further infrastructure (not shown) as intermediaries. The OTT connection 1124 may be transparent in the sense that the participating communication devices through which the OTT connection 1124 passes are unaware of routing of uplink and downlink communications. For example, the base station 1106 may not or need not be informed about the past routing of an incoming downlink communication with data originating from the host computer 1116 to be forwarded (e.g., handed over) to a connected UE 1112. Similarly, the base station 1106 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1112 towards the host computer 1116.

[0146] Example implementations, in accordance with an embodiment, of the UE, base station, and host computer discussed in the preceding paragraphs will now be described with reference to Figure 12. In a communication system 1200, a host computer 1202 comprises hardware 1204 including a communication interface 1206 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 1200. The host computer 1202 further comprises processing circuitry 1208, which may have storage and / or processing capabilities. In particular, the processing circuitry 1208 may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The host computer 1202 further comprises software 1210, which is stored in or accessible by the host computer 1202 and executable by the processing circuitry 1208. The software 1210 includes a host application 1212. The host application 1212 may be operable to provide a service to a remote user, such as a UE 1214 connecting via an OTT connection 1216 terminating at the UE 1214 and the host computer 1202. In providing the service to the remote user, the host application 1212 may provide user data which is transmitted using the OTT connection 1216.

[0147] The communication system 1200 further includes a base station 1218 provided in a telecommunication system and comprising hardware 1220 enabling it to communicate with the host computer 1202 and with the UE 1214. The hardware 1220 may include a communication interface 1222 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 1200, as well as a radio interface 1224 for setting up and maintaining at least a wireless connection 1226 with the UE 1214 located in a coverage area (not shown in Figure 12) served by the base station 1218. The communication interface 1222 may be configured to facilitate a connection 1228 to the host computer 1202. The connection 1228 may be direct or it may pass through a core network (not shown in Figure 12) of the telecommunication system and / or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware 1220 of the base station 1218 further includes processing circuitry 1230, which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The base station 1218 further has software 1232 stored internally or accessible via an external connection.

[0148] The communication system 1200 further includes the UE 1214 already referred to. The UE’s 1214 hardware 1234 may include a radio interface 1236 configured to set up and maintain a wireless connection 1226 with a base station serving a coverage area in which the UE 1214 is currently located. The hardware 1234 of the UE 1214 further includes processing circuitry 1238, which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The UE 1214 further comprises software 1240, which is stored in or accessible by the UE 1214 and executable by the processing circuitry 1238. The software 1240 includes a client application 1242. The client application 1242 may be operable to provide a service to a human or nonhuman user via the UE 1214, with the support of the host computer 1202. In the host computer 1202, the executing host application 1212 may communicate with the executing client application 1242 via the OTT connection 1216 terminating at the UE 1214 and the host computer 1202. In providing the service to the user, the client application 1242 may receive request data from the host application 1212 and provide user data in response to the request data. The OTT connection 1216 may transfer both the request data and the user data. The client application 1242 may interact with the user to generate the user data that it provides.

[0149] It is noted that the host computer 1202, the base station 1218, and the UE 1214 illustrated in Figure 12 may be similar or identical to the host computer 1116, one of the base stations 1106A, 1106B, 1106C, and one of the UEs 1112, 1114 of Figure 11, respectively. This is to say, the inner workings of these entities may be as shown in Figure 12 and independently, the surrounding network topology may be that of Figure 11. In Figure 12, the OTT connection 1216 has been drawn abstractly to illustrate the communication between the host computer 1202 and the UE 1214 via the base station 1218 without explicit reference to any intermediary devices and the precise routing of messages via these devices. The network infrastructure may determine the routing, which may be configured to hide from the UE 1214 or from the service provider operating the host computer 1202, or both. While the OTT connection 1216 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

[0150] The wireless connection 1226 between the UE 1214 and the base station 1218 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 1214 using the OTT connection 1216, in which the wireless connection 1226 forms the last segment.

[0151] A measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 1216 between the host computer 1202 and the UE 1214, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection 1216 may be implemented in the software 1210 and the hardware 1204 of the host computer 1202 or in the software 1240 and the hardware 1234 of the UE 1214, or both. In some embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 1216 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which the software 1210, 1240 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 1216 may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not affect the base station 1218, and it may be unknown or imperceptible to the base station 1218. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer’s 1202 measurements of throughput, propagation times, latency, and the like. The measurements may be implemented in that the software 1210 and 1240 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 1216 while it monitors propagation times, errors, etc.

[0152] Figure 13 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 11 and 12. For simplicity of the present disclosure, only drawing references to Figure 13 will be included in this section. In step 1300, the host computer provides user data. In sub-step 1302 (which may be optional) of step 1300, the host computer provides the user data by executing a host application. In step 1304, the host computer initiates a transmission carrying the user data to the UE. In step 1306 (which may be optional), the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1308 (which may also be optional), the UE executes a client application associated with the host application executed by the host computer.

[0153] Figure 14 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 11 and 12. For simplicity of the present disclosure, only drawing references to Figure 14 will be included in this section. In step 1400 of the method, the host computer provides user data. In an optional sub-step (not shown) the host computer provides the user data by executing a host application. In step 1402, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1404 (which may be optional), the UE receives the user data carried in the transmission.

[0154] Figure 15 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 11 and 12. For simplicity of the present disclosure, only drawing references to Figure 15 will be included in this section. In step 1500 (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step 1502, the UE provides user data. In sub-step 1504 (which may be optional) of step 1500, the UE provides the user data by executing a client application. In sub-step 1506 (which may be optional) of step 1502, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in sub-step 1508 (which may be optional), transmission of the user data to the host computer. In step 1510 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

[0155] Figure 16 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 11 and 12. For simplicity of the present disclosure, only drawing references to Figure 16 will be included in this section. In step 1600 (which may be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step 1602 (which may be optional), the base station initiates transmission of the received user data to the host computer. In step 1604 (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station.

[0156] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc.

[0157] Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0158] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

[0159] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

Claims1. A method performed by a User Equipment, UE, (206), comprising: generating (304; 418) a measurement report for a target cell (204-T), the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell (204-R) for the target cell (204-T); and transmitting (304; 418) the measurement report to a Radio Access Network, RAN, node (202-T; 202) that operates the target cell (204-T).

2. The method of claim 1, wherein the target cell (204-T) is subject to Clear Channel Assessment, CCA.

3. The method of claim 1 or 2, wherein generating (304; 418) the measurement report for the target cell (204-T) is responsive to there being a need to obtain measurements on the reference cell for use for measurement reporting for the target cell (204-T) due to Clear Channel Assessment, CCA, failure on the target cell (204-T).

4. The method of claim 1 or 2, further comprising determining (300; 412) that there is a need to obtain measurements on the reference cell for use for measurement reporting for the target cell (204-T) due to Clear Channel Assessment, CCA, failure on the target cell (204-T).

5. The method of claim 3 or 4, wherein the need to obtain measurements on a reference cell for use for measurement reporting for the target cell (204-T) due to CCA failure on the target cell (204-T) is determined based on one or more first criteria.

6. The method of claim 5, wherein the one or more first criteria comprise a criterion that the UE (206) does not detect any downlink reference signal or any one of a defined set of downlink reference signals in the target cell (204-T) during a time interval that is longer than a predefined or configured time interval threshold.

7. The method of claim 5 or 6, wherein the one or more first criteria comprise a criterion that the UE (206) detects one or more signals in the target cell (204-T) but a corresponding measured value on the one or more detected signals is less than a predefined or configured threshold measurement value in a time interval longer than a predefined or configured time interval threshold.

8. The method of any of claims 5 to 7, wherein the one or more first criteria comprise a criterion that the UE (206) detects samples of one or more signals in the target cell (204-T) but cannot complete a full measurement in a time interval longer than a predefined or configured time interval threshold.

9. The method of any of claims 6 to 8, wherein the time interval begins at a time at which the UE (206) last successfully detected and measured a downlink reference signal or one of a defined set of downlink reference signals in the target cell (204-T).

10. The method of any of claims 1 to 9, further comprising identifying (302; 414) the reference cell (204-R) for the target cell (204-T).

11. The method of claim 10, wherein identifying (302; 414) the reference cell (204-R) for the target cell (204-T) comprises identifying (302; 414) the reference cell (204-R) for the target cell (204-T) based on one or more second criteria.

12. The method of claim 11, wherein the one or more second criteria comprise a criterion that a measured power for a downlink reference signal in the reference cell (204-R) is higher than a predefined or configured power threshold.

13. The method of claim 11 or 12, wherein the one or more second criteria comprise a criterion that a measured power for a downlink reference signal in the reference cell (204-R) is higher than a predefined or configured power threshold, at least no earlier than a predefined or configured time interval threshold before the UE (206) enables measurement reporting for the target cell (204-T) including measurements, or adjusted versions of the measurements, from a reference cell (204-R).

14. The method of any of claims 11 to 13, wherein the one or more second criteria comprise a criterion that a last valid spatial relation of the UE (206) with respect to the target cell (204-T) is the same or sufficiently similar to a spatial relation of the UE (206) relative to the reference cell (204-R).

15. The method of any of claims 11 to 13, wherein the one or more second criteria comprise a criterion that a last valid spatial relation of the UE (206) with respect to the target cell (204-T) is the same or sufficiently similar to a spatial relation of the UE (206) relative to the reference cell (204-R), at least no earlier than a predefined or configured time interval threshold before the UE (206) enables measurement reporting for the target cell (204-T) including measurements, or adjusted versions of the measurements, from a reference cell (204-R).

16. The method of any of claims 11 to 15, wherein the one or more second criteria comprise a criterion that a last valid timing or Doppler characteristic detected by the UE (206) with respect to the target cell (204-T) is the same as or sufficiently similar to that of the reference cell (204-R).

17. The method of any of claims 11 to 15, wherein the one or more second criteria comprise a criterion that a last valid timing or Doppler characteristic detected by the UE (206) with respect to the target cell (204-T) is the same as or sufficiently similar to that of the reference cell (204-R), no earlier than a predefined or configured time interval before the UE (206) enables measurement reporting for the target cell (204-T) including measurements, or adjusted versions of the measurements, from a reference cell (204-R).

18. The method of any of claims 11 to 17, wherein the one or more second criteria comprise a criterion that a difference between a last valid power measurement of a reference signal on the target cell (204-T) performed by the UE (206) and that of the reference cell (204-R) is less than a predefined or configured threshold and both are higher than a power threshold.

19. The method of any of claims 11 to 17, wherein the one or more second criteria comprise a criterion that a difference between a last valid power measurement of a reference signal on the target cell (204-T) performed by the UE (206) and that of the reference cell (204-R) is less than a predefined or configured threshold and both are higher than a power threshold, no earlier than a predefined or configured time interval before the UE (206) enables measurement reporting for the target cell (204-T) including measurements, or adjusted versions of the measurements, from a reference cell (204-R).

20. The method of any of claims 1 to 19, further comprising transmitting (420), to the RAN node (202-T; 202), an indication that the measurement report comprises one or more measurements that are based on one or more measurements performed on the reference cell (204-R).

21. The method of any of claims 1 to 20, wherein the target cell (204-T) operates on a carrier in an unlicensed frequency band, and the reference cell (204-R) operates on a carrier in a licensed frequency band.

22. A User Equipment, UE, (206) adapted to: generate (304; 418) a measurement report for a target cell (204-T), the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell (204-R) for the target cell (204-T); and transmit (304; 418) the measurement report to a Radio Access Network, RAN, node (202-T; 202) that operates the target cell (204-T).

23. The UE (206) of claim 22, wherein the UE (206) is further adapted to perform the method of any of claims 2 to 21.

24. A User Equipment, UE, (206; 900) comprising:one or more transmiters (908); one or more receivers (910); and processing circuitry (902) associated with the one or more transmiters (908) and the one or more receivers (910), the processing circuitry (902) configured to cause the UE (206; 900) to: generate (304; 418) a measurement report for a target cell (204-T), the measurement report comprising one or more measurements that are or are based on one or more measurements performed on one or more downlink reference signals on a reference cell (204-R) for the target cell (204-T); and transmit (304; 418) the measurement report to a Radio Access Network, RAN, node (202- T; 202) that operates the target cell (204-T).

25. The UE (206; 900) of claim 24, wherein the processing circuitry (902) is further configured to cause the UE (206; 900) to perform the method of any of claims 2 to 21.

26. A method performed by a Radio Access Network, RAN, node (202; 202-T), comprising: obtaining (504) one or more measurements for a User Equipment, UE, (206) on a target cell(204-T) using one or more measurements of the UE (206) on a reference cell (204-R) for the target cell (204-T) and / or one or more measurements of a reference UE on the target cell (204-T); and. using (504) the one or more measurements obtained for the UE (206) on the target cell (204-T) for one or more operations.

27. The method of claim 26, wherein the target cell (204-T) is subject to Clear Channel Assessment, CCA.

28. The method of claim 26 or 27, wherein obtaining (500) the one or more measurements for the UE on the target cell (204-T) is responsive to there being a need to obtain measurements on the reference cell for the target cell (204-T) and / or the reference UE on a target cell (204-T) for use for measurements for the UE (206) on the target cell (204-T) due to CCA failure for the UE (206) on the target cell (204-T).

29. The method of claim 26 or 27, further comprising determining (500) that there is a need to obtain measurements on the reference cell for the target cell (204-T) and / or the reference UE on a target cell (204-T) for use for measurements for the UE (206) on the target cell (204-T) due to CCA failure for the UE (206) on the target cell (204-T).

30. The method of claim 29, wherein the need to obtain measurements on the reference cell and / or the reference UE on the target cell (204-T) for use for measurements for the UE (206) on the target cell (204- T) due to CCA failure for the UE (206) on the target cell (204-T) is determined based on one or more first criteria.

31. The method of claim 30, wherein the one or more first criteria comprise a criterion that the RAN node (202; 202-T) does not detect any uplink reference signal or any one of a defined set of uplink reference signals from the UE (206) in the target cell (204-T) during a time interval that is longer than a predefined or configured time interval threshold.

32. The method of claim 30 or 31, wherein the one or more first criteria comprise a criterion that the RAN node (202; 202-T) detects one or more signals from the UE (206) in the target cell (204-T) but a corresponding measured value on the one or more detected signals is less than a predefined or configured threshold measurement value in a time interval longer than a predefined or configured time interval threshold.

33. The method of any of claims 30 to 32, wherein the one or more first criteria comprise a criterion that the RAN node (202; 202-T) detects samples of one or more signals from the UE (206) in the target cell (204-T) but cannot complete a full measurement in a time interval longer than a predefined or configured time interval threshold.

34. The method of any of claims 31 to 33, wherein the time interval begins at a time at which the RAN node (202; 202-T) last successfully detected and measured an uplink reference signal or one of a defined set of uplink reference signals from the UE (206) in the target cell (204-T).

35. The method of any of claims 26 to 34, further comprising identifying (502) the reference cell (204-R) for the target cell (204-T) or the reference UE for the UE (206) on the target cell (204-T).

36. A Radio Access Network, RAN, node (202; 202-T) adapted to: obtain (504) one or more measurements for a User Equipment, UE, (206) on a target cell (204-T) using one or more measurements of the UE (206) on a reference cell (204-R) for the target cell (204-T) and / or one or more measurements of a reference UE on the target cell (204-T); and use (504) the one or more measurements obtained for the UE (206) on the target cell (204-T) for one or more operations.

37. The RAN node (202; 202-T) of claim 36, further adapted to perform the method of any of claims 27 to 35.

38. A Radio Access Network, RAN, node (202; 202-T) comprising: processing circuitry (604); and memory (606) storing instructions executable by the processing circuitry (604) whereby the RAN node (202; 202-T) is operable to:obtain (504) one or more measurements for a User Equipment, UE, (206) on a target cell (204-T) using one or more measurements of the UE (206) on a reference cell (204-R) for the target cell (204-T) and / or one or more measurements of a reference UE on the target cell (204-T); and use ( 04) the one or more measurements obtained for the UE (206) on the target cell(204-T) for one or more operations.

39. The RAN node (202; 202-T) of claim 38, wherein by execution of the instructions by the processing circuitry (604), the RAN node (202; 202-T) is further operable to perform the method of any of claims 27 to 35.

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